Batman Returns. Keaton was great as Bats once again, Pfeiffer totally killed it as Catwoman, and Devito was having so much fun that he's just fun to watch every moment that he's on screen. And when he's not hamming it up, he does a great job at portraying the tormented, raging, alienated side of Burton's Penguin.

Extra points for the penguin army marching with rockets and the iconic image of Bruce Wayne standing in front of the projected bat signal.

This is one of those movies that people seem to either love or hate, and there's lots of people that can't stand it. I think it was better than the first, personally. Burton had more passion for it because they let him do what he wanted to do, and that passion really shines through. Not only would I say that it's underrated, I'd also say that (on the big screen, at least) it's the most unique take on a mainstream superhero's world that we've ever been given.